Hardening induced by radiation damage and helium in structural materials

Irradiation is known to lead to degradation of mechanical properties of materials. Structural materials for nuclear applications can be affected by helium produced by transmutations. The objectives of this work were: (a) to investigate the effects of He on the mechanical properties of steels in different irradiation conditions (neutron spallation source and He-implantation), (b) to study the irradiation-induced hardening effect and the contribution of He on the hardening, (c) to compare the barrier strength of helium bubbles to moving dislocations as well as that of defect clusters and (d) to interpret the individual and combined barrier strengths to the overall hardening contribution. These goals have been reached by performing detailed hardness measurements on F82H ferritic/martensitic (f/m) steel after spallation neutron irradiation to 6.2-20.3 dpa (displacement per atom) at 151-344 °C and to a He-concentration of 465-1825 appm (atomic part per million) as well as after annealing treatments (300 °C/1 h, 400 °C/1 h, 600 °C/1 h and 600 °C/200 h). The annealing treatments were applied to remove the defect clusters stepwise and make the He-bubbles grow. Austenitic steel SS316L and f/m steels F82H and Optifer, helium implanted (0.2 dpa , 1350 appm He) with a 28 MeV He-beam at room temperature and after annealing were used to gain complementary information on the barrier strength of the helium bubbles. A significant increase in hardness following irradiation and implantation was observed: the largest increase in hardening was observed for the specimen with the highest received dose and He concentration. In comparison to the as-irradiated specimens, the hardness values of the annealed specimens were distinctively lower. The annealing demonstrated a continuously decrease with increasing annealing temperature. Detailed transmission electron microscopy (TEM) has been performed on STIP-II irradiated specimens in the as-irradiated condition and after annealing at 600 °C/1 h and 600 °C/200 h as well as on He-implanted specimens in their annealed condition. These investigations provided quantitative information on size distribution and density of defect clusters and helium bubbles as a function of irradiation dose, helium concentration and irradiation temperature. The helium bubbles were found to be weaker obstacles to dislocation than the defect clusters whereas their contribution to irradiation hardening cannot be neglected owing to their high density. Scanning transmission electron microscopy in combination with electron energy loss spectroscopy was performed on selected specimens. These investigations provided quantitative information on the helium number density

Le paganisme de Maurice Guérin dans le Centaure

Vieh J. A. Le paganisme de Maurice Guérin dans le Centaure. In: Cahiers de l'Association internationale des études francaises, 1958, n°10. pp. 211-223

THE APPLICATION OF MUON TOMOGRAPHY TO SAFETY AND SAFEGUARDING IN GEOLOGICAL REPOSITORIES

Muon tomography is a technique that harnesses naturally occurring cosmic radiation to perform non-invasive andnon-destructive imaging of otherwise inaccessible objects. The paper will consider the application of muon tomography toaspects of the monitoring of nuclear waste with a focus on safety and safeguards in a geological repository (GR). Muontomography is capable of providing critical information on the overburden of a prospective underground facility and wouldbe able to identify unknown features such as voids or undocumented tunnels not declared before the construction of a GR.The paper will present the results from simulations that address some of these questions and, in particular, whichexplore the limitations in the muon tomography technique (measurement time, detector resolution, etc.). The paper will alsosummarise a series of experiments proposed for the Grimsel Test Site that will help to develop an empirical understanding ofhow this exciting technology may complement the "Safety and Safeguards measurement tool kit”

The Use of Muon Tomography in Safeguarding Nuclear Geological Disposal Facilities

Muon attenuation tomography is a powerful tool that employs naturally occurring cosmic ray muons for locating, identifying, and measuring density irregularities in geological overburdens. First applied in the 1950s [3], the technique has very many diverse applications including imaging civil infrastructure such as railway tunnels [4], identifying ore bodies in mines, monitoring magma chambers in volcanoes [5], and identifying voids in pyramids [6, 7]. Muon scattering tomography, which requires the muons to be tracked both entering and leaving the object of interest, can provide valuable information on the atomic number, Z, of objects being imaging in addition to density information. The following reports on a series of simulation studies we have performed to assess the capability of muon radiography to detect a series of potential features that may need to be identified for safeguarding or safety purposes in geological disposal facilities (GDFs) for nuclear waste. Similarly, the application of muon scattering tomography to characterizing the materials encased in nuclear waste drums and to assessing unauthorized diversion scenarios is also presented

Reduzierung geruchsintensiver Emissionen eines Schlachthofes durch den Einsatz eines Biofilters einschliesslich Be- und Entlueftungsanlagen Abschlussbericht

TIB Hannover: FR 3562 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman